1. Field of the Invention
The present invention relates, in general, to a fan clutch for a vehicle and, more particularly, to a fan clutch for a vehicle which can minimize the amount of oil that has been supplied into an actuation chamber before an engine is started, thereby improving both the cold start performance and the acceleration performance of the vehicle.
2. Description of Related Art
Typically, a cooling fan is a device that is installed in an engine compartment of a vehicle and functions to improve the cooling efficiency of cooling water charged in a radiator, thereby allowing the cooling water circulating in the engine to be maintained at a constant temperature.
The cooling fans for vehicles are typically classified into automatic fan type devices and mechanical fan clutch type devices. Of the related art cooling fans, the mechanical fan clutch type device is configured such that it responds to the temperature of the cooling water charged in the radiator, and drives a cooling fan only when the temperature of the cooling water is higher than a predetermined temperature.
FIG. 1 is a sectional view illustrating the construction of a conventional liquid fan clutch for a vehicle.
As shown in FIG. 1, the conventional fan clutch includes: a fan housing 10 that is formed by assembling left and right housing parts into a single body, and a rotor 40 that is installed in the inner space of the fan housing 10 such that the rotor 40 can be rotated. The rotor 40 is connected to a rotating shaft 20 such that the rotor 40 can be rotated by the drive force of an engine which is transmitted from an engine crankshaft (not shown).
Here, a bearing 30 is set between the fan housing 10 and rotating shaft 20, so, when the rotating shaft 20 is being rotated, the fan housing 10 is not rotated by the rotating force of the rotating shaft 20.
The inner space of the fan housing 10 is divided into an oil storage chamber S and an actuation chamber D by a partition plate 50. In the fan housing 10, oil is stored in the oil storage chamber S, and the rotor 40 is installed in the actuation chamber D. Further, an oil supply valve 60 is installed on a side surface of the partition plate 50, and functions to feed oil from the oil storage chamber S to the actuation chamber D. In FIG. 1, the reference numeral 61 denotes a pulley, and the reference numeral 70 denotes an oil line.
Due to the above-mentioned construction, when the rotating shaft 20 is rotated, the rotor 40 is rotated in the actuation chamber D of the fan housing 10. In the above state, the oil supply valve 60 is opened and feeds oil from the oil storage chamber S to the actuation chamber D, so a viscosity resistance is produced in the actuation chamber D by the oil, and this causes the fan housing 10 to be rotated along with the rotor 40. Here, the rotating speed of the fan housing 10 is increased in proportion to an increase in the viscosity resistance that is produced in the actuation chamber D by the oil, in which the increase in the viscosity resistance is in proportion to an increase in the amount of oil charged in the actuation chamber D, and reduces the slipping of the fan housing 10 relative to the rotating rotor 40.
However, in the related art technique, before starting the vehicle, oil that has been stored in the oil storage chamber flows from the oil storage chamber into the actuation chamber through a return line due to gravity.
Accordingly, the related art technique is problematic in that, when starting the vehicle in the above-mentioned state, both the rotor and the fan housing are rotated at the same time due to the viscosity resistance of oil that has been introduced into the actuation chamber, so a shearing force is generated in the fan clutch and the load imposed on a starter is increased when the vehicle is started.
Further, due to the above-mentioned problem, the cooling fan is not separated from the fan clutch when initially starting the vehicle, and the rpm of the cooling fan is increased following an increase in the engine rpm, so the acceleration performance of the vehicle is reduced.
The foregoing is intended merely to aid in the understanding of the background of the present invention, and is not intended to mean that the present invention falls within the purview of the related art that is already known to those skilled in the art.
The information disclosed in this Background of the Invention section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.